Biden's 2024 campaign unraveled in 25 days. From debating Trump to endorsing Harris, here are the key events that led to his exit from the race.

On Sunday, President Biden announced he would be ending his campaign for a second term after almost a month of pressure from congressional Democrats.

“It has been the greatest honor of my life to serve as your president,” Mr. Biden said in a letter posted on social media. “And while it has been my intention to seek reelection, I believe it is in the best interest of my party and the country for me to stand down and to focus solely on fulfilling my duties as president for the remainder of my term.”

Biden’s age has been a central concern to his campaign against former President Donald Trump, and his debate performance on June 27 only exacerbated doubts about his ability to beat Trump and carry out out a second term.

In less than a month, Biden went from confidently committing to seeing his campaign through to Election Day to announcing his decision to step aside and endorse Vice President Kamala Harris instead. Here are the events that led up to Biden’s historic move.

Thursday, June 27

Biden and Trump debate for the first time since 2020. The 81-year-old president seeks to use the forum to demonstrate to his supporters and naysayers alike that he was equipped to win again in November and serve a second term.

Instead, the 90-minute debate resulted in Democratic Party panic over Biden’s ability to defeat Trump in the upcoming election.

Read more from Yahoo News: How did Trump and Biden do in the presidential debate? 3 takeaways from 2024's 1st big clash.

Friday, June 28

Biden addresses criticism of his debate performance at a campaign stop in North Carolina.

“I know I’m not a young man,” he said. “I don’t walk as easy as I used to, I don’t speak as smoothly as I used to, I don’t debate as well as I used to, but I know what I do know. I know how to tell the truth.”

Sunday, June 30

Biden's team goes on the offensive with congressional allies making appearances across several major talk shows to promote Biden's candidacy.

Tuesday, July 2

Rep. Lloyd Doggett is the first member of Congress to call on Biden to drop out of the presidential race. Over the next few weeks, more than 35 congressional Democrats would follow suit.

A Yahoo News/YouGov poll finds that 60% of Americans don't think Biden is fit for another term as president.

Friday, July 5

Biden makes his first primetime appearance since the debate in an interview with ABC News’s George Stephanopoulos.

In a campaign rally in Wisconsin, Biden says, “Let me say it as clearly as I can: I’m staying in the race.”

Read more from Yahoo News:6 takeaways from Biden's high-stakes interview with ABC News' George Stephanopoulos

Monday, July 8

Congress returns from break and Biden writes a two-page letter to Democrats about his commitment to staying in the race "and to beating Donald Trump."

Wednesday, July 10

Former House Speaker Nancy Pelosi, who had been a vocal supporter of Biden staying in the race as late as June 30, starts to backtrack. In an interview with MSNBC's Morning Joe, she says, "It's up to the president to decide if he's going to run."

Sen. Peter Welch becomes the first Senate Democrat to call on Biden to step down. Actor, filmmaker and Democratic activist George Clooney publishes an op-ed in the New York Times saying, "We are not going to win in November with this president" — just weeks after he co-hosted a fundraiser for Biden.

Thursday, July 11

Biden hosts a post-NATO press conference and makes a few glaring mistakes. He accidentally refers to Harris as "Vice President Trump," just hours after he introduced Ukrainian President Volodymyr Zelensky as Russian President Vladimir Putin.

House Minority Leader Hakeem Jeffries has a meeting with Biden where he "directly expressed the full breadth of insight, heartfelt perspectives and conclusions about the path forward that the Caucus has shared in our recent time together," the Washington Post reports.

Saturday, July 13

While at a campaign rally in Butler, Pa., a gunman opens fire in an attempt to assassinate Trump, injuring the former president along with two other attendees, and killing one rallygoer. Biden’s campaign cancels TV ads and events out of respect.

Sunday, July 14

Biden addresses the Trump rally shooting from the Oval Office.

“I want to speak to you tonight about the need for us to lower the temperature in our politics,” Biden said. “We're neighbors or friends, co-workers, citizens. Most importantly, we are fellow Americans, we must stand together.”

Tuesday, July 16

In an interview with BET News, Biden says that only a medical condition would convince him to reconsider staying in the race.

The White House reports that Biden has been diagnosed with COVID, forcing him to cancel a campaign appearance in Las Vegas.

Thursday, July 18

It’s the last day of the Republican National Convention and Trump gives his first speech since his assassination attempt a few days prior.

Read more from Yahoo News: 2024 RNC: Trump delivers a message of 'unity' in speech — until he doesn't

Friday, July 19

Bloomberg reports that members of the Biden administration Cabinet have private discussions about Biden's chances of beating Trump. Biden-Harris campaign chair Jennifer O'Malley Dillon tells MSNBC's Morning Joe that "the president is still in the race" and "he's not going anywhere."

White House spokesman Andrew Bates denies reports that Biden's family has started discussing an exit plan.

Sunday, July 21

Biden calls Harris, White House chief of staff Jeff Zients and O'Malley Dillon to tell them he's going to announce he's dropping out of the race, the New York Times reports. He drafts his announcement letter and publishes it on X at 1:46 p.m. ET — just one minute after he reportedly informed his senior staff of the decision.

Less than an hour later, Biden publicly endorses Harris to become the Democratic presidential nominee.